U.S. patent application number 17/420983 was filed with the patent office on 2022-03-31 for tearable dressing structure.
The applicant listed for this patent is KCI Licensing, Inc.. Invention is credited to Christopher Brian LOCKE, Timothy Mark ROBINSON.
Application Number | 20220096730 17/420983 |
Document ID | / |
Family ID | 1000006048234 |
Filed Date | 2022-03-31 |
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United States Patent
Application |
20220096730 |
Kind Code |
A1 |
ROBINSON; Timothy Mark ; et
al. |
March 31, 2022 |
Tearable Dressing Structure
Abstract
A dressing or wound filler comprising a laminate structure of
materials. In one example embodiment, a dressing may include a
first layer comprising a first film, a second layer adjacent to the
first layer and comprising a foam, and a third layer comprising a
second film. The first layer and the second layer may further
include a plurality of perforations or fenestrations. The third
layer may include a plurality of raised features. The perforations
or fenestrations of the first and second layers may be positioned
or aligned with the raised features of the third layer so as to
facilitate tearing of the dressing for sizing and application
purposes. In some embodiments, the first layer may comprise a
polyurethane film, the second layer may comprise a polyurethane
foam, and the third layer may comprise an additional polyurethane
film.
Inventors: |
ROBINSON; Timothy Mark;
(Shillingstone, GB) ; LOCKE; Christopher Brian;
(Bournemouth, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KCI Licensing, Inc. |
San Antonio |
TX |
US |
|
|
Family ID: |
1000006048234 |
Appl. No.: |
17/420983 |
Filed: |
January 7, 2020 |
PCT Filed: |
January 7, 2020 |
PCT NO: |
PCT/US2020/012560 |
371 Date: |
July 6, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62797632 |
Jan 28, 2019 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 13/0216 20130101;
A61F 2013/00357 20130101; A61L 15/425 20130101; A61M 1/915
20210501; A61F 13/0206 20130101; A61L 15/26 20130101 |
International
Class: |
A61M 1/00 20060101
A61M001/00; A61F 13/02 20060101 A61F013/02; A61L 15/26 20060101
A61L015/26; A61L 15/42 20060101 A61L015/42 |
Claims
1. A dressing material, comprising: a first layer comprising a
first film of non-porous material having a plurality of openings; a
second layer adjacent to the first layer, the second layer
comprising a manifold having a plurality of slits; and a third
layer adjacent to the second layer and comprising a second film of
non-porous material having raised features; wherein at least some
of the plurality of openings, some of the plurality of slits, and
some of the raised features are aligned to define a tear line.
2. The dressing material of claim 1, wherein the first film
comprises a polyurethane material.
3. The dressing material of claim 1, wherein the manifold comprises
a polyurethane foam.
4. The dressing material of claim 1, wherein: the first film
comprises a polyurethane material; and the second film comprises a
polyurethane material.
5. The dressing material of claim 1, wherein: the plurality of
openings and the plurality of slits are configured as pairs of
aligned openings and slits.
6. (canceled)
7. (canceled)
8. The dressing material of claim 1, wherein the first film is an
adhesive-coated film.
9. The dressing material of claim 1, wherein: the plurality of
openings are distributed across the first layer in parallel rows
and columns; and the rows are spaced about 3 mm on center.
10. The dressing material of claim 1, wherein: the plurality of
openings are distributed across the first layer in parallel rows
and columns; the rows are spaced 3 mm on center; and the openings
in each of the rows are spaced about 3 mm on center.
11. The dressing material of claim 10, wherein the plurality of
openings in adjacent rows are offset.
12. The dressing material of claim 1, wherein: the second film is
an adhesive-coated film; and the second film is laminated to the
second layer.
13. The dressing material of claim 1, wherein the second film is a
highly-breathable film.
14. The dressing material of claim 1, wherein at least some of the
plurality of openings, some of the plurality of slits, and some of
the raised features are aligned in a circular pattern.
15. The dressing material of claim 1, wherein at least some of the
plurality of openings, some of the plurality of slits, and some of
the raised features are aligned in a linear pattern.
16. The dressing material of claim 1, wherein at least some of the
plurality of openings, some of the plurality of slits, and some of
the raised features are aligned in a pattern having geometric
shapes.
17. The dressing material of claim 16, wherein the geometric shapes
comprise one or more squares or circles.
18. (canceled)
19. The dressing material of claim 1, wherein the plurality of
openings are distributed across the first layer in perpendicular
rows.
20.-45. (canceled)
46. A system for treating a tissue site, comprising: a wound
filler, comprising: a first layer comprising a first film of
non-porous material, a second layer adjacent to the first layer,
the second layer comprising foam, a third layer adjacent to the
second layer and comprising a second film of non-porous material
having raised features, and a plurality of fenestrations extending
through the first layer and the second layer; a plurality of
sealing strips adapted to be positioned over a perimeter of the
third layer opposite the second layer; and an interface adapted to
be coupled to the wound filler.
47. The system of claim 46, further comprising a negative-pressure
source adapted to be fluidly connected to the wound filler through
the interface.
48. The system of claim 46, wherein: the first film comprises a
polyurethane material; and the foam comprises a polyurethane
foam.
49. The system of claim 46, wherein each of the plurality of
fenestrations has a length between 1 mm and 5 mm.
50. (canceled)
Description
RELATED APPLICATIONS
[0001] The present application claims priority to U.S. Provisional
Patent Application No. 62/797,632, entitled "Tearable Dressing
Structure," filed Jan. 28, 2019, which is incorporated herein by
reference for all purposes.
TECHNICAL FIELD
[0002] The invention set forth in the appended claims relates
generally to tissue treatment systems and more particularly, but
without limitation, to dressings for tissue treatment and methods
of using the dressings for tissue treatment.
BACKGROUND
[0003] Clinical studies and practice have shown that reducing
pressure in proximity to a tissue site can augment and accelerate
growth of new tissue at the tissue site. The applications of this
phenomenon are numerous, but it has proven particularly
advantageous for treating wounds. Regardless of the etiology of a
wound, whether trauma, surgery, or another cause, proper care of
the wound is important to the outcome. Treatment of wounds or other
tissue with reduced pressure may be commonly referred to as
"negative-pressure therapy," but is also known by other names,
including "negative-pressure wound therapy," "reduced-pressure
therapy," "vacuum therapy," "vacuum-assisted closure," and "topical
negative-pressure," for example. Negative-pressure therapy may
provide a number of benefits, including migration of epithelial and
subcutaneous tissues, improved blood flow, and micro-deformation of
tissue at a wound site. Together, these benefits can increase
development of granulation tissue and reduce healing times.
[0004] While the clinical benefits of negative-pressure therapy are
widely known, improvements to therapy systems, components, and
processes may benefit healthcare providers and patients.
BRIEF SUMMARY
[0005] New and useful systems, apparatuses, and methods for
treating tissue in a negative-pressure therapy environment are set
forth in the appended claims. Illustrative embodiments are also
provided to enable a person skilled in the art to make and use the
claimed subject matter.
[0006] For example, in some embodiments, a dressing or wound filler
may comprise a laminate structure of materials. Outer layers may
comprise film layers, at least one of which may be configured to
face a tissue site. For example, the outer layers may comprise a
polyurethane film. At least one of the outer layers may have linear
perforations or fenestrations formed over the surface. The size and
spacing of the perforations or fenestrations may vary. Another of
the outer layers may comprise a film having raised features. One or
more intermediate spacing layers between the outer layers may
comprise a polymer foam, such as a polyurethane foam, which may
manifold fluid, provide a compressible filler that can conform to
spaces and curves, and can present a barrier to tissue in-growth.
An intermediate foam layer may comprise perforations or
fenestrations that align with the perforations or fenestrations in
the first outer film layer and the raised features of the second
outer layer in order to facilitate tearing of the laminate
structure.
[0007] More generally, in some embodiments, a dressing material may
include a first layer comprising a first film of non-porous
material having a plurality of openings, a second layer adjacent to
the first layer and comprising a manifold having a plurality of
slits, and a third layer adjacent to the second layer and
comprising a second film of non-porous material having raised
features. At least some of the plurality of openings, some of the
plurality of slits, and some of the raised features may be aligned
to define a tear line. In some embodiments, the first layer may
comprise a polyurethane film, the second layer may comprise a
polyurethane foam, and the third layer may comprise a polyurethane
film.
[0008] In other example embodiments, a dressing for treating a
tissue site with negative pressure may comprise a foam layer
comprising a first plurality of fenestrations, a first film
comprising a second plurality of fenestrations, and a second film
comprising a plurality of raised features. The first film may be
positioned adjacent the first side of the foam layer, and the
second film may be positioned adjacent the second side of the foam
layer. In some embodiments, the first plurality of fenestrations
and the second plurality of fenestrations may be aligned.
[0009] In still further example embodiments, a method of
manufacturing a dressing material may include laminating a first
film to a first side of a foam layer, creating a plurality of
fenestrations through the first film and the foam layer, and
laminating a second film comprising a plurality of raised features
to a second side of the foam layer. In some embodiments, at least a
portion of the plurality of raised features of the second film are
aligned with at least a portion of the plurality of fenestrations.
In some embodiments, creating the plurality of fenestrations may
include forming the fenestrations in parallel rows and columns. In
some additional embodiments, creating the plurality of
fenestrations may include forming fenestrations in a pattern having
geometric shapes.
[0010] In yet further example embodiments, a system for treating a
tissue site may include a wound filler, a plurality of sealing
strips, and an interface. The wound filler may include a first
layer comprising a first film of non-porous material, a second
layer adjacent to the first layer and comprising a foam, a third
layer adjacent to the second layer and comprising a second film of
non-porous material having raised features, and a plurality of
fenestrations extending through the first layer and the second
layer. The plurality of sealing strips may be adapted to be
positioned over a perimeter of the third layer opposite the second
layer. The interface may be adapted to be coupled to the wound
filler. The system may further include a negative-pressure source
adapted to be fluidly connected to the wound filler through the
interface.
[0011] Objectives, advantages, and a preferred mode of making and
using the claimed subject matter may be understood best by
reference to the accompanying drawings in conjunction with the
following detailed description of illustrative embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is an assembly view of an example of a tissue
interface, illustrating details that may be associated with some
example embodiments;
[0013] FIG. 2 is a schematic view of an example configuration of
fluid openings in a layer that may be associated with some
embodiments of the tissue interface of FIG. 1;
[0014] FIG. 3 is a schematic view of an example configuration of
raised features in another layer that may be associated with some
embodiments of the tissue interface of FIG. 1;
[0015] FIG. 4 is a schematic view of a portion of the example layer
of FIG. 3 overlaid on a portion of another layer that may be
associated with some embodiments of the tissue interface of FIG. 1,
illustrating details that may be associated with a relaxed state of
the layers;
[0016] FIG. 5 is a schematic view of the overlaid layers shown in
FIG. 4, illustrating details that may be associated with a
stretched state of the layers;
[0017] FIG. 6 is a schematic view of overlaid layers associated
with some embodiments of the tissue interface of FIG. 1,
illustrating details that may be associated with tearing through
portions of the overlaid layers;
[0018] FIG. 7 is another schematic view of overlaid layers
associated with some embodiments of the tissue interface of FIG. 1,
illustrating details that may be associated with tearing through
portions of the overlaid layers;
[0019] FIG. 8 is an assembly view of an example of a dressing that
may incorporate the tissue interface of FIG. 1, according to some
illustrative embodiments; and
[0020] FIG. 9 is a functional block diagram of an example
embodiment of a therapy system that can provide negative-pressure
treatment in accordance with this specification.
DESCRIPTION OF EXAMPLE EMBODIMENTS
[0021] The following description of example embodiments provides
information that enables a person skilled in the art to make and
use the subject matter set forth in the appended claims, but it may
omit certain details already well-known in the art. The following
detailed description is, therefore, to be taken as illustrative and
not limiting.
[0022] The example embodiments may also be described herein with
reference to spatial relationships between various elements or to
the spatial orientation of various elements depicted in the
attached drawings. In general, such relationships or orientation
assume a frame of reference consistent with or relative to a
patient in a position to receive treatment. However, as should be
recognized by those skilled in the art, this frame of reference is
merely a descriptive expedient rather than a strict
prescription.
[0023] FIG. 1 is an assembly view of an example of a tissue
interface 100 for applying to a tissue site. The tissue interface
100 can be generally adapted to partially or fully contact a tissue
site. If the tissue site is a wound, for example, the tissue
interface 100 may partially or completely fill the wound, or may be
placed over the wound. The tissue interface 100 may have a first
side 105 and a second side 115. The tissue interface 100 may
include a first layer 110, a second layer 120, and a third layer
130. In some embodiments, the first layer 110, the second layer
120, and the third layer 130 may be stacked so that the second
layer 120 is adjacent to and in contact with the first layer 110
and the third layer 130. The second layer 120 may also be laminated
or bonded to the first layer 110, the third layer 130, or both in
some embodiments. In some embodiments, the first layer 110 may be
adapted to be placed against a tissue site, such as a wound and
surrounding periwound area.
[0024] The tissue interface 100 may take many forms, and may have
many sizes, shapes, or thicknesses, depending on a variety of
factors, such as the type of treatment being implemented or the
nature and size of a tissue site. While the tissue interface 100 is
shown in FIG. 1 overall to have substantially a square shape, the
tissue interface 100 and included layers may be any number of
different shapes, based on the particular anatomical needs of a
tissue site. For example, the tissue interface 100 and included
layers may have a square, rectangular, oval, circular, hexagonal,
or other shape. For example, the size and shape of the tissue
interface 100 may be adapted to the contours of deep and irregular
shaped tissue sites. Any or all of the surfaces of the tissue
interface 100 may have an uneven, coarse, or jagged profile.
[0025] The term "tissue site" in this context broadly refers to a
wound, defect, or other treatment target located on or within
tissue, including, but not limited to, bone tissue, adipose tissue,
muscle tissue, neural tissue, dermal tissue, vascular tissue,
connective tissue, cartilage, tendons, or ligaments. A wound may
include chronic, acute, traumatic, subacute, and dehisced wounds,
partial-thickness burns, ulcers (such as diabetic, pressure, or
venous insufficiency ulcers), flaps, and grafts, for example. The
term "tissue site" may also refer to areas of any tissue that are
not necessarily wounded or defective, but are instead areas in
which it may be desirable to add or promote the growth of
additional tissue.
[0026] The first layer 110 may comprise or consist essentially of a
means for controlling or managing fluid flow. In some embodiments,
the first layer 110 may comprise or consist essentially of a
liquid-impermeable material. For example, the first layer 110 may
comprise or consist essentially of a non-porous polymer film. The
first layer 110 may also have a smooth or matte surface texture in
some embodiments. In some embodiments, variations in surface height
may be limited to acceptable tolerances. For example, the surface
of the first layer 110 may have a substantially flat surface, with
height variations limited to 0.2 millimeters over a centimeter.
[0027] In some embodiments, the first layer 110 may comprise or
consist essentially of a polymeric film. In some embodiments, the
first layer 110 may comprise or consist essentially of a
hydrophilic polymeric film, while in additional or alternative
embodiments, the first layer 110 may comprise or consist
essentially of a hydrophobic polymeric film. In some embodiments,
the first layer 110 may comprise or consist essentially of a
polyurethane film. For example, the first layer 110 may comprise an
Inspire 2301 or Inspire 2327 polyurethane film, commercially
available from Expopack Advanced Coatings, Wrexham, United Kingdom.
In some applications, the first layer 110 may have a high
moisture-vapor transmission rate (MVTR). For example, the MVTR may
be at least 250 grams per square meter per twenty-four hours in
some embodiments, measured using an upright cup technique according
to ASTM E96/E96M Upright Cup Method at 38.degree. C. and 10%
relative humidity (RH). For example, the first layer 110 may
comprise INSPIRE 2301 having an MVTR (upright cup technique) of
2600 g/m.sup.2/24 hours and a thickness of about 30 microns. Other
suitable polymeric films may include polyethylenes, acrylics,
polyolefin (such as cyclic olefin copolymers), polyacetates,
polyamides, polyesters, copolyesters, PEBAX block copolymers,
thermoplastic elastomers, thermoplastic vulcanizates, polyethers,
polyvinyl alcohols, polypropylene, polymethylpentene,
polycarbonate, styreneics, silicones, fluoropolymers, and acetates.
A thickness between 20 microns and 100 microns may be suitable for
many applications. Films may be clear, colored, or printed. In some
embodiments where the first layer 110 may comprise a polyethylene
film, more polar films suitable for laminating to a polyethylene
film include polyamide, copolyesters, ionomers, and acrylics. To
aid in the bond between a polyethylene and polar film, tie layers
may be used, such as ethylene vinyl acetate, or modified
polyurethanes. An ethyl methyl acrylate (EMA) film may also have
suitable hydrophobic and welding properties for some
configurations. In some embodiments, the hydrophobicity of the
first layer 110 may be further enhanced with a hydrophobic coating
of other materials, such as silicones and fluorocarbons, either as
coated from a liquid or plasma coated.
[0028] In some embodiments, the first layer 110 may comprise an
adhesive coating, which may be exposed on the first side 105 of the
tissue interface 100. In some embodiments, the adhesive coating may
comprise a low-tack medically-acceptable adhesive. For example, the
adhesive coating may comprise a silicone gel, a polyurethane gel,
or a low-tack acrylic adhesive. In some instances, the adhesive
coating may have a low coat weight, such as between 25 grams per
square meter and 100 grams per square meter, which may maintain the
high MVTR of the first layer 110. The thickness of the adhesive
coating may be tailored to balance the need to provide a good seal
with the tissue site, while also maintaining a high MVTR. The
adhesive coating may also be pattern coated on the first layer 110
in order to maintain the high MVTR of the first layer 110. The
adhesive coating may assist with keeping the tissue interface 100
in place during application, which may be helpful to the user while
finalizing the placement of the tissue interface 100 and sealing
the tissue interface 100 to the tissue site.
[0029] The first layer 110 may also be suitable for laminating,
adhering, or welding to other layers, including the second layer
120. For example, the first layer 110 may be flame laminated to the
second layer 120. The first layer 110 may also be secured to the
second layer 120 using a non-woven or mesh hot-melt material. For
example, a nonwoven or mesh hot-melt material may be applied to the
surface of the second layer 120, with the first layer 110 being
applied over the hot-melt material. Heat and pressure may then be
applied to melt the nonwoven or mesh hot-melt material in order to
bind the first layer 110 to the second layer 120. In some
embodiments, the first layer 110 may be adapted for welding to the
second layer 120, which may be a foam, using heat, radio-frequency
(RF) welding, or other methods to generate heat such as ultrasonic
welding. RF welding may be particularly suitable for more polar
materials, such as polyurethane, polyamides, polyesters, and
acrylates. Sacrificial polar interfaces may be used to facilitate
RF welding of less polar film materials such as polyethylene. In
some additional or alternative embodiments, the first layer 110 may
comprise a film having an adhesive coating on a surface for
adhering to the second layer 120.
[0030] As illustrated in the example of FIG. 1, the first layer 110
may have one or more openings 140, which may be distributed
uniformly across the first layer 110. The openings 140 may be
bi-directional and pressure-responsive. For example, each of the
openings 140 generally may comprise or consist essentially of an
elastic passage that is normally unstrained to substantially reduce
liquid flow, and can expand or open in response to a pressure
gradient. The openings 140 may be in the form of fenestrations or
perforations. In some embodiments, the openings 140 may comprise or
consist essentially of fenestrations in the first layer 110.
Fenestrations may be formed by removing material from the first
layer 110, and may result in edges that are not deformed. In some
alternative or additional embodiments, the openings 140 may
comprise or consist essentially of perforations in the first layer
110. Perforations may be formed by removing material from the first
layer 110. For example, perforations may be formed by cutting
through the first layer 110. The amount of material removed and the
resulting dimensions of the perforations may be an order of
magnitude more than fenestrations, which may result in edges that
are deformed. Additionally, in some embodiments, perforations may
be formed by mechanical slitting then controlled uni- and/or
bi-axial stretching of the film material of the first layer
110.
[0031] For example, some embodiments of the openings 140 may
comprise or consist essentially of one or more slits, slots, or
combinations of slits and slots in the first layer 110. In some
examples, the openings 140 may comprise or consist of linear slots
having a length less than 6 millimeters and a width less than 1
millimeter. The length may be at least 2 millimeters, and the width
may be at least 0.4 millimeters in some embodiments. A length of
about 3 millimeters and a width of about 0.8 millimeters may be
particularly suitable for many applications, and a tolerance of
about 0.1 millimeter may also be acceptable. Such dimensions and
tolerances may be achieved with a laser cutter, ultrasonics, or
other heat means, for example. The linear slits or slots may be
spaced apart by about 2 to 4 millimeters along their length and
from side-to-side.
[0032] The second layer 120 generally comprises or consists
essentially of a manifold or a manifold layer, which provides a
means for collecting or distributing fluid across the tissue
interface 100 under pressure. For example, the second layer 120 may
be adapted to receive negative pressure from a source and
distribute negative pressure through multiple apertures across the
tissue interface 100, which may have the effect of collecting fluid
from across a tissue site and drawing the fluid toward the
source.
[0033] In some illustrative embodiments, the second layer 120 may
comprise a plurality of pathways, which can be interconnected to
improve distribution or collection of fluids. In some embodiments,
the second layer 120 may comprise or consist essentially of a
porous material having interconnected fluid pathways. For example,
cellular foam, open-cell foam, reticulated foam, porous tissue
collections, and other porous material such as gauze or felted mat
generally include pores, edges, and/or walls adapted to form
interconnected fluid channels. Liquids, gels, and other foams may
also include or be cured to include apertures and fluid
pathways.
[0034] In some embodiments, the second layer 120 may comprise or
consist essentially of a polymeric foam, such as a polyurethane
foam. For example, the second layer 120 may comprise or consist
essentially of reticulated foam having pore sizes and free volume
that may vary according to needs of a prescribed therapy. For
example, reticulated foam having a free volume of at least 90% may
be suitable for many therapy applications, and foam having an
average pore size in a range of 400-600 microns (40-50 pores per
inch) may be particularly suitable for some types of therapy. The
tensile strength of second layer 120 may also vary according to
needs of a prescribed therapy. The 25% compression load deflection
of the second layer 120 may be at least 0.35 pounds per square
inch, and the 65% compression load deflection may be at least 0.43
pounds per square inch. In some embodiments, the tensile strength
of the second layer 120 may be at least 10 pounds per square inch.
The second layer 120 may have a tear strength of at least 2.5
pounds per inch. In some embodiments, the second layer 120 may be
foam comprised of polyols such as polyester or polyether,
isocyanate such as toluene diisocyanate, and polymerization
modifiers such as amines and tin compounds. In some examples, the
second layer 120 may be reticulated polyurethane foam such as found
in GRANUFOAM.TM. dressing or V.A.C. VERAFLO.TM. dressing, both
available from Kinetic Concepts, Inc. of San Antonio, Tex.
[0035] In some additional or alternative embodiments, the second
layer 120 may be hydrophilic and may also wick fluid away from a
tissue site, while being able to continue to distribute a negative
pressure to the tissue site. The wicking properties of the second
layer 120 may draw fluid away from a tissue site by capillary flow
or other wicking mechanisms. An example of a hydrophilic material
that may be suitable is a polyvinyl alcohol, open-cell foam such as
V.A.C. WHITEFOAM.TM. dressing available from Kinetic Concepts, Inc.
of San Antonio, Tex. Other hydrophilic foams may include those made
from polyether. Other foams that may exhibit hydrophilic
characteristics include hydrophobic foams that have been treated or
coated to provide hydrophilicity.
[0036] The thickness of the second layer 120 may also vary
according to needs of a prescribed therapy. For example, the
thickness of the second layer 120 may be decreased to reduce
tension on peripheral tissue. The thickness of the second layer 120
can also affect the conformability of the second layer 120 and the
tissue interface 100. In some embodiments, a thickness in a range
of about 4 millimeters to 12 millimeters may be suitable, and in
some more specific embodiments, the second layer 120 may have a
thickness between 6 millimeters and 10 millimeters. In some
embodiments, the second layer 120 may be partially or completely
opaque, or otherwise be such that the second layer 120 may block at
least a portion of light passage.
[0037] As illustrated in the example of FIG. 1, the second layer
120 may include a plurality of slits 150, which may be distributed
uniformly across the second layer 120. The slits 150 may be in the
form of fenestrations or tears through a portion or the entire
thickness of the second layer 120. For example, the second layer
120 may comprise a reticulated polyurethane foam having slits 150
in the form of finely-cut linear fenestrations. In some
embodiments, the slits 150 may be arranged in parallel rows, which
may be offset from each other in some instances. In some additional
embodiments, the slits 150 may be arranged in both parallel and
perpendicular rows. The slits 150 may correspond to or be aligned
with at least some of the openings 140 in the first layer 110. In
some examples, the slits 150 may comprise or consist of linear
fenestrations having a length of between 1 millimeter and 6
millimeters, and a width less than 1 millimeter. In some
embodiments, a length of about 3 millimeters may be particularly
suitable for many applications, and a tolerance of about 0.1
millimeters may also be acceptable. The slits 150 may be spaced
apart by about 2 millimeters to 4 millimeters along their length
and from side-to-side between the adjacent rows of the slits 150,
in some examples.
[0038] The slits 150 of the second layer 120 may be formed using a
variety of mechanisms. For example, the slits 150 may be formed
using a knife or other blade to make fine cuts in the second layer
120. In such instances, the slits 150 may have a virtually
negligible width, as little to none of the material of the second
layer 120 is removed during the cutting with the knife or other
form of blade. In other embodiments, the slits 150 may be formed
using laser cutting, which may result in the slits 150 having a
width of between 0.3 mm and 0.5 mm in some instances. Using laser
cutting may evaporate the material of the second layer 120 in order
to form the slit 150, without leaving any appreciable amount of
material of the second layer 120 behind. In other embodiments,
ultrasonic cutting may be used to form the slits 150 in the second
layer 120.
[0039] The third layer 130 may be constructed from a material that
can provide a seal between two environments, such as between a
therapeutic environment and a local external environment. For
example, the third layer 130 may be adapted to provide a sealing
layer over the first layer 110 and the second layer 120 of the
tissue interface 100, and the material of the third layer 130 may
be capable of maintaining a negative pressure at a tissue site. The
third layer 130 may generally comprise or consist essentially of a
film layer formed from a soft, flexible material. In some
embodiments, the third layer 130 may be constructed from a thin
film that is highly-breathable. For example, the third layer 130
may comprise an elastomeric film that can provide a seal for
maintaining a negative pressure at a tissue site. The third layer
130 may have a high moisture-vapor transmission rate (MVTR) in some
embodiments. In some example embodiments, the third layer 130 may
be a polyurethane film that is permeable to water vapor, but
impermeable to liquid. For example, the third layer 130 may
comprise a film formed from a polyurethane copolymerized with an
elastane in order to increase the stretching capability of the
third layer 130. In some additional embodiments, the third layer
130 may comprise, for example, a polyethylene, polyester, or
copolyester film. In some embodiments, the film of the third layer
130 may have a thickness in the range of 25-50 microns.
[0040] The third layer 130 may include a first side 160 and a
second side 165. In some embodiments, the first side 160 may
comprise an adhesive coating for adhering to an upper-facing side
of the second layer 120. For example, the adhesive coating may be a
medically-acceptable acrylic adhesive. The third layer 130 may also
include a plurality of raised features 170. For example, the raised
features 170 may be formed as a plurality of embossed protrusions
on the second side 165 of the third layer 130. In some embodiments,
the raised features 170 may be in the form of a plurality of raised
features arranged in a series of parallel rows. For example, the
raised features 170 may comprise a plurality of textured, raised
hemispheres, and may have a diameter in a range between 0.5
millimeters and 5 millimeters. Other shapes and sizes for the
raised features 170 may also be applicable. The raised features 170
may be spaced apart between about 1 millimeter and 5 millimeters
within rows, and may be spaced side-to-side by about 1 millimeter.
The raised features 170 may further enhance the breathability of
the film of the third layer 130.
[0041] In some additional or alternative embodiments, the third
layer 130 may comprise a material that has raised features 170 as
well as a plurality of perforations. For example, the third layer
130 may be a Transpore.TM. surgical tape, supplied by 3M of
Maplewood, Minn. In such embodiments, an additional sealing layer
may be included over the third layer 130 on the second side 115 of
the tissue interface 100 in order to provide a sealed environment
around the other layers of the tissue interface 100 for maintaining
a negative pressure.
[0042] The first layer 110, the second layer 120, the third layer
130, or various combinations may be assembled before application or
in situ. In some embodiments, the tissue interface 100 may be
manufactured and/or provided in its assembled, stacked
configuration, for example with the first layer 110 laminated to
the second layer 120, and the third layer 130 also laminated to the
second layer 120 opposite the first layer 110. In some instances,
the first layer 110 may be laminated to the second layer 120, and
then perforations or fenestrations may be made through both of the
laminated layers to form the openings 140 of the first layer 110
and the slits 150 of the second layer 120. In some alternative
embodiments, the openings 140 may be first made in the first layer
110, and the slits 150 may be separately made in the second layer
120, before the first layer 110 and the second layer 120 are
laminated together in a stacked configuration.
[0043] In some embodiments, the layers of the tissue interface 100
may be coextensive. For example, the first layer 110 may be flush
with the edges of the second layer 120 and with the edges of the
third layer 130, exposing the edges of the second layer 120 between
the first layer 110 and the third layer 130, as illustrated in the
embodiment of FIG. 1. In some alternative embodiments, one or more
of the layers of the tissue interface 100 may not be coextensive
with each other. The laminated stack of tissue interface layers may
allow the tissue interface 100 to be sized by simultaneously
tearing through the stacked layers of the tissue interface 100.
[0044] FIG. 2 is a schematic view of an example of the first layer
110, illustrating additional details that may be associated with
some embodiments. As illustrated in the example of FIG. 2, the
openings 140 may each consist essentially of one or more linear
slots having a length D.sub.1, which may be about 3 millimeters.
FIG. 2 additionally illustrates an example of a uniform
distribution pattern of the openings 140. In FIG. 2, the openings
140 are substantially coextensive with the first layer 110 and are
distributed across the first layer 110 in a grid of parallel rows
and columns, in which the slots are also mutually parallel to each
other. In some embodiments, the rows may be spaced by a distance
D.sub.2, which may be about 3 millimeters on center, and the
openings 140 within each of the rows may be spaced by a distance
D.sub.3, which may be about 3 millimeters on center as illustrated
in the example of FIG. 2. The openings 140 in adjacent rows may be
aligned or offset. For example, adjacent rows may be offset, as
illustrated in FIG. 2, so that the openings 140 are aligned in
alternating rows and separated by a distance D.sub.4, which may be
about 6 millimeters. The spacing of the openings 140 may vary in
some embodiments to increase the density of the openings 140
according to therapeutic requirements. Although not shown in FIG.
2, the openings 140 of the first layer 110 may be arranged in a
variety of different patterns. For example, in some alternative
embodiments, the openings 140 may be arranged in a grid with
perpendicular rows. In some further embodiments, the openings 140
may be arranged in geometric patterns or shapes to facilitate
tearing of the first layer 110 (and the other layers of the tissue
interface 100) in squares, circles, spirals, or other geometric
shapes. For example, the slits 150 of the second layer 120 may be
arranged in rows or geometric patterns corresponding to the
arrangement of the openings 140 of the first layer 110.
[0045] FIG. 3 is a schematic view of an example of the third layer
130, illustrating additional details that may be associated with
some embodiments. The first side 160 of the third layer 130 may
have an adhesive coating in some examples. As illustrated in FIG.
3, the raised features 170 may be arranged in a uniform
distribution pattern, and the raised features 170 may be
substantially coextensive with the third layer 130. Similarly to
the openings 140 of the first layer 110 of FIG. 2, the raised
features 170 may be arranged across the third layer 130 in a grid
of parallel rows and columns. The rows of raised features 170 may
be spaced corresponding to the spacing of the rows of openings 140
of the first layer 110, to generally align the rows of raised
features 170 and the rows of openings 140 of the first layer 110,
which may facilitate tearing through the tissue interface 100. In
some embodiments, the raised features 170, along with the openings
140 of the first layer 110 and the slits 150 of the second layer
120, may be arranged in both parallel and perpendicular rows, in
order to facilitate tearing and sizing of the tissue interface 100
in multiple directions. The raised features 170 may also be
arranged in geometric patterns or shapes, such as squares, circles,
or spirals, so that the raised features 170 may align with the
openings 140 of the first layer 110 and slits 150 of the second
layer 120 that are arranged in such a geometric pattern, in order
to facilitate tearing and sizing the tissue interface 100 in such
shapes and patterns.
[0046] FIG. 4 is a schematic view of an example of the second layer
120 and the third layer 130, according to some embodiments. In the
representative illustration of FIG. 4, the third layer 130 has been
partially removed to expose a portion of the second layer 120, with
the remaining section of the third layer 130 being adhered or
laminated to the second layer 120. FIG. 4 illustrates portions of
the second layer 120 having slits 150 and the third layer 130
having raised features 170, where the second layer 120 and the
third layer 130 are in a relaxed, or non-stretched state. In the
pictured relaxed state, the slits 150 may be difficult to observe
due to the nature of the foam material of the second layer 120. At
least some of the rows of the raised features 170 of the third
layer 130 may be aligned with or overlaid on rows of slits 150 of
the second layer 120 to facilitate even and aligned tearing of the
second layer 120 and the third layer 130.
[0047] FIG. 5 is a schematic view of the example portions of the
second layer 120 and the third layer 130 of FIG. 4, showing
additional details according to some illustrative embodiments. In
the representative illustration of FIG. 5, a portion of the third
layer 130 has been removed to expose a portion of the second layer
120. Specifically, FIG. 5 illustrates the portion of the second
layer 120 in a non-relaxed, or stretched state. As shown in FIG. 5,
upon being stretched, the slits 150 of the second layer 120 may
become significantly more visible. As such, by at least slightly
stretching a portion of the second layer 120, one or more rows of
the slits 150 may be readily identifiable, which may assist with
determining the appropriate point to tear the second layer 120 for
purposes of sizing the tissue interface 100. Such visualization may
also allow a row of raised features 170 of the third layer 130 to
be aligned with the row of slits 150 along which the tissue
interface 100 may be torn. Such alignment of the raised features
170 of the third layer 130 and the row of slits 150 of the second
layer 120 may ensure that torn edges of the second layer 120 and
the third layer 130, and overall the tissue interface 100, are
substantially flush with each other.
[0048] FIG. 6 is a schematic view of an example portion of a tissue
interface 100, showing some details that may be viewed from a
top-facing or second side 115 of the tissue interface 100,
according to some illustrative embodiments. More specifically, FIG.
6 illustrates how an example of the tissue interface 100 may be
sized by tearing through the third layer 130, second layer 120, and
underlying first layer 110 along a desired tear line 610 of the
tissue interface 100. For example, a tear line 610 may exist where
at least a portion of a row of openings 140 of the first layer 110,
a portion of a row of slits 150 of the second layer 120, and a
portion of a row of raised features 170 of the third layer 130 are
aligned. However, the individual openings 140, slits 150, and
raised features 170 along the respective rows of openings 140,
slits 150, and raised features 170 do not necessarily have to align
with each other between the first layer 110, the second layer 120,
and the third layer 130. Additionally, not all rows of openings
140, slits 150, and raised features 170 may correspond to a tear
line. As illustrated in the example of FIG. 6, portions of the
first layer 110, the second layer 120, and the third layer 130 may
be torn along the tear line 610, corresponding to a row of the
openings 140, a row of the slits 150, and a row of the raised
features 170. Through such tearing and separation of the portions
of the first layer 110, second layer 120, and third layer 130, the
layers of the tissue interface 100 may be sized to a corresponding
tissue site.
[0049] FIG. 7 is a schematic view of the example portion of the
tissue interface 100 of FIG. 6, showing further details that may be
viewed from the first side 105 of the tissue interface 100,
according to some illustrative embodiments. More specifically, the
view of the first side 105 of the tissue interface 100 of FIG. 7
illustrates how the first layer 110 may also be torn along the tear
line 610 of the tissue interface 100, which may align with a row of
openings 140 of the first layer 110. As collectively shown by FIGS.
6 and 7, the tissue interface 100 may be torn along the tear line
610, which may correspond to and align with a row of openings 140
of the first layer 110, a row of slits 150 of the second layer 120,
and a row of raised features 170 of the third layer 130.
[0050] FIG. 8 is an assembly view of a dressing 800 which may
incorporate an embodiment of the tissue interface 100 of FIG. 1,
according to some illustrative embodiments. For example, the
dressing 800 may include the tissue interface 100, along with
additional components that may enable or particularly facilitate
use of the dressing 800 and associated tissue interface 100 with
negative-pressure therapy. As shown in FIG. 8, the dressing 800 may
comprise the tissue interface 100, which may include the first
layer 110, the second layer 120, and the third layer 130 arranged
in a stacked formation.
[0051] As shown in FIG. 8, in some embodiments, the dressing 800
may include a plurality of sealing strips 805, which may be
positioned around the perimeter of the tissue interface 100 and
sealed to an attachment surface, such as epidermis peripheral to a
tissue site, to provide an effective seal around the edges of the
tissue interface 100. The sealing strips 805 may be applied to a
perimeter of the third layer 130. For example, four individual
sections of sealing strips 805 may be used to seal the third layer
130 to an epidermis, with each of the four sections of sealing
strips 805 being applied to one of the four edges of the third
layer 130. In some embodiments, the sealing strips 805 may comprise
polymer strips, such as polyurethane strips, having an adhesive,
such as an acrylic adhesive, thereon. In some embodiments, the
sealing strips 805 may further or alternatively include additional
layers, such as a gel layer.
[0052] As illustrated in the example of FIG. 8, in some
embodiments, the dressing 800 may include a release liner 810 to
protect the first side 105 of the tissue interface 100 prior to
use. The release liner 810 may also provide stiffness to assist
with, for example, deployment of the dressing 800. The release
liner 810 may be, for example, a casting paper, a film, or
polyethylene. Further, in some embodiments, the release liner 810
may be a polyester material such as polyethylene terephthalate
(PET) or similar polar semi-crystalline polymer. The use of a polar
semi-crystalline polymer for the release liner 810 may
substantially preclude wrinkling or other deformation of the
dressing 800. For example, the polar semi-crystalline polymer may
be highly orientated and resistant to softening, swelling, or other
deformation that may occur when brought into contact with
components of the dressing 800 or when subjected to temperature or
environmental variations, or sterilization. Further, a release
agent may be disposed on a side of the release liner 810 that is
configured to contact the first layer 110 on the first side 105 of
the tissue interface 100. For example, the release agent may be a
silicone coating and may have a release factor suitable to
facilitate removal of the release liner 810 by hand and without
damaging or deforming the dressing 800. In some embodiments, the
release agent may be a fluorocarbon or a fluorosilicone, for
example. In other embodiments, the release liner 810 may be
uncoated or otherwise used without a release agent.
[0053] FIG. 8 also illustrates one example of a fluid conductor 820
and a dressing interface 830. As shown in the example of FIG. 8,
the fluid conductor 820 may be a flexible tube, which can be
fluidly coupled on one end to the dressing interface 830. The
dressing interface 830 may be an elbow connector, as shown in the
example of FIG. 8, which can be placed over an aperture on the
upper, or second side 115 of the tissue interface 100 to provide a
fluid path between the fluid conductor 820 and the tissue interface
100. For example, such an aperture may be a centrally-positioned
aperture in the third layer 130 that is cut or torn by a user. In
some embodiments, the fluid conductor 820 may also include a fluid
delivery conduit for use with instillation therapy. Further, in
some embodiments, the dressing interface 830 may include multiple
fluid conduits, such as a conduit for communicating negative
pressure and a fluid delivery conduit. For example, the dressing
interface 830 may be a V.A.C. VERAT.R.A.C..TM. Pad or a
SENSAT.R.A.C..TM. Pad, available from KCI of San Antonio, Tex.
[0054] Individual components of the tissue interface 100, and more
generally the dressing 800, may be bonded or otherwise secured to
one another with a solvent or non-solvent adhesive, or with thermal
welding, for example, without adversely affecting fluid management.
In some embodiments of the tissue interface 100, one or more
components may additionally be treated with an antimicrobial agent.
For example, the first layer 110, the second layer 120, and/or the
third layer 130 may be coated with an antimicrobial agent. In some
examples, the fluid conductor 820, the dressing interface 830, or
other portion of the dressing 800 may additionally or alternatively
be treated with one or more antimicrobial agents. Suitable agents
may include, for example, metallic silver, PHMB, iodine or its
complexes and mixes such as povidone iodine, copper metal
compounds, chlorhexidine, or some combination of these materials.
Additionally or alternatively, one or more of the components of the
tissue interface 100 may be coated with a mixture that may include
citric acid and collagen, which can reduce bio-films and
infections.
[0055] In additional embodiments, the dressing 800 may be provided
with different combinations of the individual layers and
components. For example, the tissue interface 100 may be provided
as a standalone product for applying to a tissue site. In some
further embodiments, individual layers of the dressing 800 may be
omitted. More specifically, in some alternative embodiments, one or
more layers of the tissue interface 100 may be omitted or
substituted for another layer. For example, in some embodiments,
the tissue interface 100 may comprise only the first layer 110 and
the second layer 120, with the film of the third layer 130 being
omitted. In such embodiments, the tissue interface 100, including
the first layer 110 and the second layer 120, may be applied to a
tissue site, with an additional sealing layer, such as a cover,
being applied over the first layer 110 and second layer 120. In
other embodiments, the tissue interface 100 may comprise a foam
layer sandwiched between two fenestrated film layers. For example,
such an embodiment may comprise the first layer 110 having openings
140, the second layer 120 comprising a polymeric foam and having
slits 150, and an additional film layer having openings, such as a
layer identical to the first layer 110. In such embodiments, the
foam layer and the two surrounding film layers may be stacked and
laminated to each other, and then subsequently, fenestrations may
be formed through all three of the layers at once using any of the
cutting techniques previously mentioned, such as laser cutting,
ultrasonics, or cutting using a knife or other blade.
[0056] In use, the tissue interface 100 may be sized to a specific
region or anatomical area through cutting or tearing. The release
liner 810 (if included) may be removed from the first side 105 of
the tissue interface 100. The tissue interface 100 may then be torn
by hand, with or without the use of any tools or instruments, along
one or more tear lines that may be formed through the multiple
layers of the tissue interface 100. For example, the tear line may
correspond to or be aligned with a row of the openings 140 of the
first layer 110, a row of slits 150 of the second layer 120, and a
row of raised features 170 of the third layer 130, so as to form a
complete tear or cut through the layers of the tissue interface
100. The tear line may be made through the layers of the tissue
interface 100 according to any pattern or shape, such as circles,
squares, etc., formed by the openings 140, slits 150, and raised
features 170. Thus, once sized, the tissue interface 100 may have a
surface area of a circle, square, rectangle, etc. The tissue
interface 100 may be torn or cut to an appropriate size without the
individual layers, such as the first layer 110, second layer 120,
and third layer 130, becoming separated from each other or falling
apart.
[0057] Once the tissue interface 100 is sized and/or shaped to the
area of the tissue site, the tissue interface 100 may be placed
within, over, on, or otherwise proximate to the tissue site,
particularly a surface tissue site and adjacent epidermis. The
first layer 110 may be interposed between the second layer 120 and
the tissue site. For example, the first layer 110 may be positioned
over a surface wound (including edges of the wound) and undamaged
epidermis to prevent direct contact between the second layer 120
and the epidermis. Treatment of a surface wound or placement of the
tissue interface 100 on a surface wound includes placing the tissue
interface 100 immediately adjacent to the surface of the body or
extending over at least a portion of the surface of the body. The
second layer 120 may be positioned between the first layer 110 and
the third layer 130, with the third layer 130 capable of
functioning, due to its lack of perforations, as an occlusive layer
or drape over the first layer 110, the second layer 120, and the
tissue site. The sealing strips 805 may then be placed around the
perimeter of the third layer 130 of the tissue interface 100 and
sealed to an attachment surface surrounding the tissue site, such
as adjacent epidermis, to enable a pneumatic seal around the tissue
site.
[0058] The geometry and dimensions of the tissue interface 100 may
vary to suit a particular application or anatomy. For example, the
geometry or dimensions of the tissue interface 100 may be adapted
to provide an effective and reliable seal against challenging
anatomical surfaces, such as an elbow or heel, at and around a
tissue site. Thus, the tissue interface 100 can provide a sealed
therapeutic environment proximate to a tissue site, substantially
isolated from the external environment. In some applications, a
filler may also be disposed between a tissue site and the first
layer 110 of the tissue interface 100. For example, if the tissue
site is a surface wound, a wound filler may be applied interior to
the periwound, and the first layer 110 may be disposed over the
periwound and the wound filler. In some embodiments, the filler may
be a manifold, such as an open-cell foam. The filler may comprise
or consist essentially of the same material as the second layer 120
in some embodiments. If not already configured, the dressing
interface 830 may be disposed over an aperture formed in the third
layer 130. The fluid conductor 820 may be fluidly coupled to the
dressing interface 830 and to a negative-pressure source, which can
reduce the pressure in the sealed therapeutic environment.
[0059] In some additional embodiments, the designs and principles
of the tissue interface 100 may also be incorporated into other
aspects of a dressing 800 or therapy system for treating a tissue
site. For example, the laminated, layered design of the tissue
interface 100 may be offered in the form of low-profile fluid
conduits that may be torn and sized in a customizable fashion. Such
conduits may be used in addition to or in place of a fluid
conductor 820 for coupling the dressing interface 830 to a
negative-pressure source. The openings 140, slits 150, and raised
features 170 of the layers of the tissue interface 100 may be
particularly useful for customizing the length of such a
low-profile conduit, depending on the particular application to a
patient. For example, some particular embodiments of the tissue
interface 100 may be formed in longer strips or rolls, to allow for
longer low-profile fluid conduits to be formed. Furthermore, in
some embodiments, the tissue interface 100 may include specific
patterns of fenestrations or other openings through the respective
layers of the tissue interface 100 to facilitate custom-sizing to
form a fluid conduit. For example, the tissue interface 100 may
include a portion having a plurality of parallel and perpendicular
rows of fenestrations, as well as an additional portion having
fenestrations in a pattern of concentric circles. The portion of
the tissue interface 100 having the concentric circles may be
formed into an interface or landing pad where either an additional
fluid conduit or possibly tissue dressing may be fluidly connected
to the customized low-profile fluid conduit.
[0060] FIG. 9 is a simplified functional block diagram of an
example embodiment of a therapy system 900 that can provide
negative-pressure therapy to a tissue site in accordance with this
specification. The therapy system 900 may include a source or
supply of negative pressure, such as a negative-pressure source
905, and one or more distribution components. A distribution
component is preferably detachable and may be disposable, reusable,
or recyclable. A dressing, such as the dressing 800, and a fluid
container, such as a container 915, are examples of distribution
components that may be associated with some examples of the therapy
system 900. The container 915 is representative of a container,
canister, pouch, or other storage component, which can be used to
manage exudates and other fluids withdrawn from a tissue site. As
illustrated in the example of FIG. 9, the dressing 800 may comprise
or consist essentially of the tissue interface 100. In some
embodiments, the dressing 800 may further include a cover 925.
[0061] In embodiments of the dressing 800 that include the cover
925, the cover 925 may provide an additional bacterial barrier and
protection from physical trauma. The cover 925 may also be
constructed from a material that can reduce evaporative losses and
provide a fluid seal between two components or two environments,
such as between a therapeutic environment and a local external
environment. The cover 925 may comprise or consist of, for example,
an elastomeric film or membrane that can provide a seal adequate to
maintain a negative pressure at a tissue site for a given
negative-pressure source. The cover 925 may have a high
moisture-vapor transmission rate (MVTR) in some applications. For
example, the MVTR may be at least 250 grams per square meter per
twenty-four hours in some embodiments, measured using an upright
cup technique according to ASTM E96/E96M Upright Cup Method at
38.degree. C. and 10% relative humidity (RH). In some embodiments,
an MVTR up to 5,000 grams per square meter per twenty-four hours
may provide effective breathability and mechanical properties. In
some embodiments, an attachment device may be used to attach the
cover 925 to an attachment surface, such as undamaged epidermis, a
gasket, or another cover. For example, an attachment device may be
a medically-acceptable, pressure-sensitive adhesive, such as an
acrylic adhesive, configured to bond the cover 925 to epidermis
around a tissue site. Other examples of an attachment device may
include a double-sided tape, paste, hydrocolloid, hydrogel,
silicone gel, or organogel.
[0062] In some example embodiments, the cover 925 may be a polymer
drape, such as a polyurethane film, that is permeable to water
vapor but impermeable to liquid. Such drapes typically have a
thickness in the range of 25-50 microns. For permeable materials,
the permeability generally should be low enough that a desired
negative pressure may be maintained. The cover 925 may comprise,
for example, one or more of the following materials: polyurethane
(PU), such as hydrophilic polyurethane; cellulosics; hydrophilic
polyamides; polyvinyl alcohol; polyvinyl pyrrolidone; hydrophilic
acrylics; silicones, such as hydrophilic silicone elastomers;
natural rubbers; polyisoprene; styrene butadiene rubber;
chloroprene rubber; polybutadiene; nitrile rubber; butyl rubber;
ethylene propylene rubber; ethylene propylene diene monomer;
chlorosulfonated polyethylene; polysulfide rubber; ethylene vinyl
acetate (EVA); co-polyester; and polyether block polymide
copolymers. Such materials are commercially available as, for
example, Tegaderm.RTM. drape, commercially available from 3M
Company, Minneapolis Minn.; polyurethane (PU) drape, commercially
available from Avery Dennison Corporation, Pasadena, Calif.;
polyether block polyamide copolymer (PEBAX), for example, from
Arkema S.A., Colombes, France; and Inspire 2301 and Inspire 2327
polyurethane films, commercially available from Expopack Advanced
Coatings, Wrexham, United Kingdom. In some embodiments, the cover
925 may comprise INSPIRE 2301 having an MVTR (upright cup
technique) of 2600 g/m.sup.2/24 hours and a thickness of about 30
microns.
[0063] The therapy system 900 may also include a regulator or
controller, such as a controller 930. Additionally, the therapy
system 900 may include sensors to measure operating parameters and
provide feedback signals to the controller 930 indicative of the
operating parameters. As illustrated in FIG. 9, for example, the
therapy system 900 may include a first sensor 935 and a second
sensor 940 coupled to the controller 930.
[0064] Some components of the therapy system 900 may be housed
within or used in conjunction with other components, such as
sensors, processing units, alarm indicators, memory, databases,
software, display devices, or user interfaces that further
facilitate therapy. For example, in some embodiments, the
negative-pressure source 905 may be combined with the controller
930 and other components into a therapy unit.
[0065] In general, components of the therapy system 900 may be
coupled directly or indirectly. Coupling may include fluid,
mechanical, thermal, electrical, or chemical coupling (such as a
chemical bond), or some combination of coupling in some
contexts.
[0066] A negative-pressure supply, such as the negative-pressure
source 905, may be a reservoir of air at a negative pressure or may
be a manual or electrically-powered device, such as a vacuum pump,
a suction pump, a wall suction port available at many healthcare
facilities, or a micro-pump, for example. "Negative pressure"
generally refers to a pressure less than a local ambient pressure,
such as the ambient pressure in a local environment external to a
sealed therapeutic environment. In many cases, the local ambient
pressure may also be the atmospheric pressure at which a tissue
site is located. Alternatively, the pressure may be less than a
hydrostatic pressure associated with tissue at the tissue site.
Unless otherwise indicated, values of pressure stated herein are
gauge pressures. References to increases in negative pressure
typically refer to a decrease in absolute pressure, while decreases
in negative pressure typically refer to an increase in absolute
pressure. While the amount and nature of negative pressure provided
by the negative-pressure source 905 may vary according to
therapeutic requirements, the pressure is generally a low vacuum,
also commonly referred to as a rough vacuum, between -5 mm Hg (-667
Pa) and -500 mm Hg (-66.7 kPa). Common therapeutic ranges are
between -50 mm Hg (-6.7 kPa) and -300 mm Hg (-39.9 kPa).
[0067] A controller, such as the controller 930, may be a
microprocessor or computer programmed to operate one or more
components of the therapy system 900, such as the negative-pressure
source 905. The controller 930 may control one or more operating
parameters of the therapy system 900, which may include the power
applied to the negative-pressure source 905, the pressure generated
by the negative-pressure source 905, or the pressure distributed to
the tissue interface 100, for example. The controller 930 is also
preferably configured to receive one or more input signals, such as
a feedback signal, and programmed to modify one or more operating
parameters based on the input signals.
[0068] Sensors, such as the first sensor 935 and the second sensor
940, are generally known in the art as any apparatus operable to
detect or measure a physical phenomenon or property, and generally
provide a signal indicative of the phenomenon or property that is
detected or measured. For example, the first sensor 935 and the
second sensor 940 may be configured to measure one or more
operating parameters of the therapy system 900. In some
embodiments, the first sensor 935 may be a transducer configured to
measure pressure in a pneumatic pathway and convert the measurement
to a signal indicative of the pressure measured. The second sensor
940 may optionally measure operating parameters of the
negative-pressure source 905, such as a voltage or current, in some
embodiments.
[0069] In operation, the tissue interface 100 may be placed within,
over, on, or otherwise proximate to a tissue site. The cover 925
may optionally be placed over the tissue interface 100 and sealed
to an attachment surface near a tissue site. For example, the cover
925 may be sealed to undamaged epidermis peripheral to a tissue
site. Thus, the dressing 800 can provide a sealed therapeutic
environment proximate to a tissue site, substantially isolated from
the external environment, and the negative-pressure source 905 can
reduce pressure in the sealed therapeutic environment.
[0070] The fluid mechanics of using a negative-pressure source to
reduce pressure in another component or location, such as within a
sealed therapeutic environment, can be mathematically complex.
However, the basic principles of fluid mechanics applicable to
negative-pressure therapy are generally well-known to those skilled
in the art, and the process of reducing pressure may be described
illustratively herein as "delivering," "distributing," or
"generating" negative pressure, for example.
[0071] In general, exudate and other fluid flow toward lower
pressure along a fluid path. Thus, the term "downstream" typically
implies something in a fluid path relatively closer to a source of
negative pressure or further away from a source of positive
pressure. Conversely, the term "upstream" implies something
relatively further away from a source of negative pressure or
closer to a source of positive pressure. Similarly, it may be
convenient to describe certain features in terms of fluid "inlet"
or "outlet" in such a frame of reference. This orientation is
generally presumed for purposes of describing various features and
components herein. However, the fluid path may also be reversed in
some applications, such as by substituting a positive-pressure
source for a negative-pressure source, and this descriptive
convention should not be construed as a limiting convention.
[0072] Negative pressure applied across the tissue site through the
tissue interface 100 in the sealed therapeutic environment can
induce macro-strain and micro-strain in the tissue site. Negative
pressure can also remove exudate and other fluid from a tissue
site, which can be collected in container 915. For example,
negative pressure applied through the tissue interface 100 can
create a negative pressure differential across the openings 140 in
the first layer 110, which can open or expand the openings 140 from
their resting state. For example, in some embodiments in which the
openings 140 may comprise substantially closed fenestrations
through the first layer 110, a pressure gradient across the
fenestrations can strain the adjacent material of the first layer
110 and increase the dimensions of the fenestrations to allow
liquid movement through them, similar to the operation of a
duckbill valve. Opening the openings 140 can allow exudate and
other liquid movement through the openings 140, through the second
layer 120, the third layer 130, and into the container 915. Changes
in pressure can also cause the second layer 120 to expand and
contract, and the first layer 110 may protect the epidermis from
irritation caused by the movement of the second layer 120. The
first layer 110 can also substantially reduce or prevent exposure
of tissue to the second layer 120, which can inhibit growth of
tissue into the second layer 120.
[0073] In some embodiments, the controller 930 may receive and
process data from one or more sensors, such as the first sensor
935. The controller 930 may also control the operation of one or
more components of the therapy system 900 to manage the pressure
delivered to the tissue interface 100. In some embodiments,
controller 930 may include an input for receiving a desired target
pressure and may be programmed for processing data relating to the
setting and inputting of the target pressure to be applied to the
tissue interface 100. In some example embodiments, the target
pressure may be a fixed pressure value set by an operator as the
target negative pressure desired for therapy at a tissue site and
then provided as input to the controller 930. The target pressure
may vary from tissue site to tissue site based on the type of
tissue forming a tissue site, the type of injury or wound (if any),
the medical condition of the patient, and the preference of the
attending physician. After selecting a desired target pressure, the
controller 930 can operate the negative-pressure source 905 in one
or more control modes based on the target pressure and may receive
feedback from one or more sensors to maintain the target pressure
at the tissue interface 100.
[0074] If the negative-pressure source 905 is removed or
turned-off, the pressure differential across the openings 140 of
the first layer 110 of the tissue interface 100 can dissipate,
allowing the openings 140 to move to their resting state and
prevent or reduce the rate at which exudate or other liquid can
return to the tissue site through the first layer 110.
[0075] The systems, apparatuses, and methods described herein may
provide significant advantages. For example, some dressings and
tissue interfaces for applying to tissue sites can require time and
skill to be properly sized and applied to achieve a good fit and
seal, in addition to requiring one or more cutting or sizing tools.
In contrast, some embodiments of the tissue interface 100 may be
applied to a tissue site with simple sizing and cutting steps,
therefore reducing the amount of time and effort as compared to
some previous dressings. For example, the tissue interface 100 may
be torn by hand, without requiring the use of scissors or scalpels.
Importantly, multiple layers of the tissue interface 100 may be
torn at once, thus obviating challenges associated with separately
sizing the individual layers and potential sizing inconsistencies
between the layers. Thus, the tissue interface 100 may offer a
fully-integrated dressing that can be easily cut and applied to a
tissue site (including over the periwound), while providing many
benefits of other dressings that may require more complex sizing
protocols. Such benefits may include good manifolding, beneficial
granulation, and protection of the peripheral tissue from
maceration. The tissue interface 100 may also conform to and occupy
a significant space at a tissue site, which may be particularly
advantageous for wounds having moderate depth and medium-to-high
levels of exudate. Additionally, the tissue interface 100 can
promote granulation while reducing the opportunity for tissue
in-growth by containing the porous foam material within other film
layers. As a result, the tissue interface 100 can be worn for
extended wear times, for example up to seven days.
[0076] The designs of some embodiments of the tissue interface 100
may also allow for a more custom- or specifically-tailored size of
the tissue interface 100 to be accomplished, as compared to some
other dressing materials commercially available, such as dressing
materials which may include only large, pre-cut sections. For
example, the plurality of the openings 140 of the first layer 110,
the slits 150 of the second layer 120, and the raised features 170
of the third layer 130 may allow for one or more tear lines to be
made through the tissue interface 100 at specific locations, thus
allowing the size of the tissue interface 100 to closely correspond
to the area or size of the tissue site to which it is to be
applied. The flexibility offered by being able to tear the tissue
interface 100 along multiple specific lines may also result in
fewer wasted dressing materials. For example, a user may make
multiple or repeated tears through the tissue interface 100 in
order to make adjustments to the size of the tissue interface 100
to accomplish an appropriate fit for the tissue site being
treated.
[0077] While shown in a few illustrative embodiments, a person
having ordinary skill in the art will recognize that the systems,
apparatuses, and methods described herein are susceptible to
various changes and modifications that fall within the scope of the
appended claims. Moreover, descriptions of various alternatives
using terms such as "or" do not require mutual exclusivity unless
clearly required by the context, and the indefinite articles "a" or
"an" do not limit the subject to a single instance unless clearly
required by the context. Components may be also be combined or
eliminated in various configurations for purposes of sale,
manufacture, assembly, or use. For example, in some configurations
the tissue interface 110, the container 915, or any other disclosed
components may be separated from other components for manufacture
or sale. In other example configurations, the controller 930 may
also be manufactured, configured, assembled, or sold independently
of other components.
[0078] The appended claims set forth novel and inventive aspects of
the subject matter described above, but the claims may also
encompass additional subject matter not specifically recited in
detail. For example, certain features, elements, or aspects may be
omitted from the claims if not necessary to distinguish the novel
and inventive features from what is already known to a person
having ordinary skill in the art. Features, elements, and aspects
described in the context of some embodiments may also be omitted,
combined, or replaced by alternative features serving the same,
equivalent, or similar purpose without departing from the scope of
the invention defined by the appended claims.
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